In the field of medical diagnosis and treatment of humans, it is desirable to provide an in vivo transverse section radio-nuclide scanning system. One such system, known as the Mark III scanner at the University of Pennsylvania is described in Radiology, Vol. 96, No. 3, pages 563-570, September 1970. In the described system there is provided a device for rectilinear and transverse section scanning of a human brain using an absorbed short-lived radionuclide, such as .sup.99m Tc.sub.43 pertechnetate, having four detectors for viewing four different aspects of the brain simultaneously without moving the human patient, and a self-contained computer for controlling the display and the automatic operations while minimizing processing delays. This system, however, was limited in the sensitivity it could achieve because it required the discrete, alternate periodic biasing of selected detectors back and forth in different directions in a sequence of stepped, linear, transverse detector motions that alternated periodically back and forth with six 15.degree. rotations of the detectors to cause the four detectors to survey the entire circumference of the head through 360.degree., as illustrated in FIG. 5 of the cited publication.